Colorado State Students Design Snowmobile for National Competition: New Engine Drastically Reduces Pollution, Fuel Consumption and Noise

Building on last year’s success at the international Clean Snowmobile Challenge, Colorado State University engineering students have developed an improved entry for the 2003 competition that decreases pollution by more than 99 percent compared to typical snowmobiles while also cutting fuel consumption over 35 percent and reducing noise to below conversational levels. The smaller and lighter 2003 model also matches or exceeds the power of today’s top-performing commercial machines.

The cost-effective engine design created by mechanical engineering students at Colorado State has the potential to dramatically reduce the environmental impact of snowmobiling. The engine technology is also being considered for reducing pollution in developing countries.

The Colorado State student team has been selected to compete against 14 other schools in the Fourth Annual Clean Snowmobile Challenge March 19-23 in Houghton, Mich. The international event challenges teams to design, build and operate modern snowmobiles to reduce emissions and noise while matching or improving the performance of machines sold on the market.

"One average commercial snowmobile produces as much air pollution as 100 cars," said Colorado State team leader Walt Hull. "Our design drastically reduces pollution while also reducing noise, increasing fuel efficiency and improving overall performance, which should appeal to everyone from environmentalists to serious snowmobilers."

Last year’s Colorado State team gained national attention by developing a fuel injected two-stroke snowmobile engine that earned first place in the best emissions portion of the competition, demonstrating that a two-stroke can be modified to reduce pollution and fuel consumption while maintaining power. However, Colorado State placed third overall in 2002 due in large part to the machine exceeding the maximum noise level by one decibel.

"This year’s team set aggressive goals to further enhance the engine, but focused primarily on the exhaust and packaging of the snowmobile, creating a machine that is 250 pounds lighter, significantly quieter and faster, and has improved handling, power and fuel economy," said team member Flint Jameson.

The Colorado State team designed and fabricated a new exhaust system that significantly decreases noise while simultaneously improving power. New custom intake silencers further help reduce the machine’s noise to about half of last year’s model. The students also integrated altitude compensation technology into the engine, eliminating the need for manual recalibration for elevation changes. Finally, belt drives were enhanced and the engine was placed in a smaller, lighter snowmobile chassis consistent with modern snowmobiles.

"Last year we set out to prove that a two-stroke engine could be modified to meet or exceed all performance criteria with the larger four-stroke engines," said team member Joel Lentz. "This year, we improved the design and created a machine that is much more relevant to the snowmobile industry to demonstrate that this technology can be integrated into the industry without any reduction in performance."

Sponsored by the Society of Automotive Engineers, the Clean Snowmobile Challenge was created to generate new ideas and technology to address growing concerns about exhaust and noise pollutants from off-road engines. The competition challenges engineering students to reengineer existing snowmobiles for improved emissions and noise while maintaining or improving performance. Competition events include emission testing, acceleration, hill climb, cold start, handling, noise measurement and fuel economy.

Bryan Willson, team adviser and research director of Colorado State’s Engines and Energy Conversion Laboratory, said the technology developed at the university has important applications beyond snowmobiling. In particular, the innovative engine design has the potential to reduce pollution in Third World countries.

"A major part of the air pollution in Asian cities is generated by vehicles with traditional two-stroke engines such as those used in snowmobiles," said Willson. "Our new cost-effective, two-stroke technology has the potential to significantly reduce pollution throughout the developing world."

Willson has been contacted by government agencies in the Philippines, India and West Africa to discuss how this type of engine can be used to reduce pollution and increase the quality of life in those countries. He has met with U.S. government officials in Washington, D.C., to discuss potential applications of this two-stroke technology in developing countries. Willson recently participated in a series of meetings in Manila hosted by the Partnership for Clean Air, an umbrella group that represents over 100 government agencies, development agencies and environmental groups seeking solutions for cleaner air in Manila. The purpose of the meetings was to develop a plan to reduce air pollution produced by millions of two-stroke engines used throughout Asia.

For more information about Colorado State’s participation in the Clean Snowmobile Challenge, visit or, to learn more about the event, visit To learn more about the innovative research at Engines and Energy Conversion Laboratory, go to